USB power meter/tester thread - YZXStudio, Power-Z, RDTech and more.

I’m ready to graduate from the more typical cheap, hard-to-read USB meter I have and onto something better, like an RD UM25 or UM34. Now trying to decide between the two.

I may be missing something, but on balance, I can’t discern why the UM34 would be favorable over the UM25, given the small price difference.

Am I missing something? Are there testing scenarios that escape my mind for which the UM34 is suitable but the UM25 is not?

The UM34 supports Dash Charge/VOOC protocols.

According to RD’s own comparison table, they both do, and the UM25 supports Huawei’s fast charge protocols in addition.

That would be a minor consideration anyway, since I don’t envision a device that utilizes yet another proprietary fast charging standard in my future. I’m fine with USB PD and hope that’s where it will be centered. QC has enough critical mass to continue, and QC4 will have PD compatibility, which will help.

On paper, the 25 is superior in almost every regard, except that it has a USB 2 and not USB 3 port, but I’m not sure how relevant that is when these meters are only taking power measurements.

That’s why I’m puzzled.

By my testing, only the UM34 supports Dash Charge/VOOC charging via a USB-A port.

Thanks. Those are the kind of nuances I seek.

The sales material associated with the early reviews of the UM25 did not indicate that support like the current table does, so I guess it was added to the UM25 in an update at some point.

Do you have the C version? I figure it’s better to have it, than regret not getting it, but the mention of ads in the smartphone app would be a bummer.

Yes, I do have the UM25C, UM34C, and recently acquired the TC66C.

Only the UM34C supports Dash Charge due to the additional pins of the USB 3 connector on that meter.

No ads in the smartphone version.

I’ve already received the RD TC66C, however when I connect it between the charger’s cable and the smartphone, it doesn’t charge:

If I connect the YZXStudio between the wall charger and the cable it charges to 1.7 amps aprox. Where could the problem be?

Does anybody know how to contact RD’s tech support? On AliExpress’s page there isn’t any email available.

RD TC66/TC66C Type-C PD trigger USB-C Voltmeter ammeter voltage 2 way current meter multimeter PD charger battery USB Tester

It seems like the data lines are not receiving any signal. It shows 0V - & + and default 1.5A DCP. The YZX meter detects the load and is forcing the charger to put out a different charging protocol and it starts to charge. There is voltage reading at the end of the cable so I guess the issue is at the phone’s side.

It could be many reasons this happens and without knowing which phone, charger and cable you’re using there’s no way to troubleshoot. Have you tried to manually trigger PD or QC 5V? In theory that should work.

Their contact info (including email) is in the Word doc.

Their email info is also included in the User Manual: 1749808860@qq.com

Which phone are you using? What firmware version is on your TC66? I believe v1.13 is the latest.

Thanks, finally got a way to contant him. Go to product page (desktop view of the website better):

RD TC66/TC66C Type-C PD trigger USB-C Voltmeter ammeter voltage 2 way current meter multimeter PD charger battery USB Tester

Then click on Contact

You need to be registered with an account at Aliexpress to be able to use private messaging.

why you use photos of UM34C when you are talking about UM24C :question:

Most UT25 has been removed from Aliexpress, we should support originals instead of copies , otherwise it will cause loss to the original creator and they may never create new products

hello,when did you buy UM25C, the latest version supports OnePlus Dash Charge

Does anyone know of a prepackaged 60W DC to USB C thing? https://www.nicelineshop.com/index.php?main_page=product_info&cPath=&products_id=8369 this is just the bare board, I’d like a case with it, if possible

Googling for “DC to USB PD Converter” might help.

Here’s one https://www.omnicharge.co/products/dc-to-usb-c-adapter/

Another in stock: Amazon.com

Cheaper one (90W): Amazon.com

This one might be your best bet:

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F113684437490

That bare board has great specs, but I find it hard to believe it would be able to handle 60W of output at lower range of input voltage for long times, say 12V which is 5A+ constant input, chargers usually get quite hot at that rate.

so sorry, we don’t have

Looks quite great, thanks! However, the size and price is a bit overkill. For such multiport usage, the MagicFox PD180 京东(JD.COM)-正品低价、品质保障、配送及时、轻松购物! is cheaper and has higher wattage.

I plan to feed it with 20V. The Lenovo 135W charger looks like great target. https://www.reddit.com/r/thinkpad/comments/bpnc9o/the_p1x1e_small_135w_charger_available_retail/

hope you get the better one

YZXstudio has a newer model ZC918P that does 160W. I bought one off ebay, but it’s also available aliexpress. Like other YZXstudio products, it’s good quality but quite expensive.

The Magic Fox PD180 looks very interesting. I think it is unique in offering PD input. Is it available anywhere more accessible than jd.com?